In plane strengths of steel columns and beam columns

Joint Venture, a joint venture of the Applied Technology Council (ATC) and the Consortium of Universities for Research in Earthquake Engineering (CUREE). While endeavoring to provide practical and accurate information, the NEHRP Consultants Joint Venture, the authors, and the reviewers assume no liability for, nor express or imply any warranty with regard to, the information contained herein. Users of information contained in this report assume all liability arising from such use. Certain commercial software, equipment, instruments, or materials may have been used in the preparation of information contributing to this report. Identification in this report is not intended to imply recommendation or endorsement by NIST, nor is it intended to imply that such software, equipment, instruments, or materials are necessarily the best available for the purpose. NIST policy is to use the International System of Units (metric units) in all its publications. In this report, however, information is presented in U.S. Customary Units (inch-pound), as this is the preferred system of units in the U.S. earthquake engineering industry. (NEHRP) " Earthquake Structural and Engineering Research " contract (SB1341-07-CQ-0019) to the NEHRP Consultants Joint Venture to conduct a variety of tasks, including Task Order 10266 entitled " Seismic Behavior and Design of Deep, Slender Wide Flange Structural Steel Beam-Column Members: Phase 1. " The objective of this task was to develop a comprehensive long-range plan to research the seismic behavior of deep, slender wide flange structural steel beam-columns in steel frames. Development of the plan included the investigation of available information on beam-column member and connection behavior in the literature, and considered the differences and interrelationships between member, subassemblage, and system performance. The resulting plan includes a summary of tasks for conducting both experimental and analytical research, and is intended to be the first step in the development of national consensus guidelines for designing and assessing the seismic performance of deep, slender wide-flange beam-columns in steel frame systems.

Research Plan for the Study of Seismic Behavior and Design of Deep, Slender Wide Flange Structural Steel Beam-Column Members

An inelastic theoretical study of the effect of biaxial partial end restraints on the response of hollow rectangular steel nonsway columns with or without biaxial crookedness and residual stresses is presented. The partial end restraints considered have linear, elastic-plastic, or trilinear moment-rotation characteristics. The fundamental total equilibrium equations for the problem are derived. An algorithm is presented based on a coupling between an iterative tangent stiffness approach and a finite-difference scheme for evaluating the spatial response of the materially nonlinear columns. The effect of partial end restraints, as well as the individual and combined influence of crookedness and residual stresses is also explained by means of load-deflection, and bending stiffness degradation curves. Several interesting conclusions are drawn regarding the behavior of columns as affected by end restraints, imperfections and slenderness.

Imperfect Columns with Biaxial Partial Restraints

Control effectiveness tests of reaction wheel actuators on a highly flexible grid are reported herein. Analytic determination of actuator control effectiveness is accomplished with finite element modelling. Experimental determination is done with two algorithms. The first is an equation error parameter identification scheme which estimates the control coefficients of the second order difference equation model of each vibration mode. The second is a least square error algorithm using the same model. For both methods there is a lack of agreement with analytic prediction.

Control effectiveness characterization for state estimation and control on a highly flexible grid

A concurrent processing algorithm is developed for materially nonlinear stability analysis of imperfect columns with biaxial partial rotational end restraints. The algorithm for solving the governing nonlinear ordinary differential equations is implemented on a multiprocessor computer called the “finite element machine”, developed at the NASA Langley Research Center. Numerical results are obtained on up to nine concurrent processors. A substantial computational gain is achieved in using the parallel processing approach.

G. Campanini

Papers

Equivalent bending moments for beam-columns